Ivey

I have my grandmothers Singer sewing machine, according to the charts I found on line I believe it is a model 66. However I was cleaning the cabinet and discovered a manual for a 99-31. Is there an easy way to tell a 66 from a 99? The serial number is AL449266, regardless of which model it is I was amazed that even without cleaning she still worked. I have taken her to my local sewing machine shop for a good cleaning and once over, I was afraid to attempt it myself!

i can't wait to get her back home and sew on her once again (I learned to sew on this very machine).

Thanks in advance for any information